Natural caloric sugars, such as sucrose, fructose and glucose, are utilized to provide a pleasant taste to beverages, foods, pharmaceuticals, and oral hygienic/cosmetic products. Sucrose, in particular, imparts a taste preferred by consumers. Although sucrose provides superior sweetness characteristics, it is caloric. Non-caloric or low caloric sweeteners have been introduced to satisfy consumer demand. However, sweeteners within this class differ from natural caloric sugars in ways that continue to frustrate consumers. On a taste basis, non-caloric or low caloric sweeteners exhibit a temporal profile, maximal response, flavor profile, mouth feel, and/or adaptation behavior that differ from sugar. Specifically, non-caloric or low caloric sweeteners exhibit delayed sweetness onset, lingering sweet aftertaste, bitter taste, metallic taste, astringent taste, cooling taste and/or licorice-like taste. On a source basis, many non-caloric or low caloric sweeteners are synthetic chemicals. The desire for a natural non-caloric or low caloric sweetener that tastes like sucrose remains high. Stevia rebaudiana is a perennial shrub of the Asteraceae (Compositae) family native to certain regions of South America. Its leaves have been traditionally used for hundreds of years in Paraguay and Brazil to sweeten local teas and medicines. The plant is commercially cultivated in Japan, Singapore, Taiwan, Malaysia, South Korea, China, Israel, India, Brazil, Australia and Paraguay.
The leaves of the plant contain a mixture containing diterpene glycosides in an amount ranging from about 10 to 20% of the total dry weight. These diterpene glycosides are about 150 to 450 times sweeter than sugar. Structurally, the diterpene glycosides are characterized by a single base, steviol, and differ by the presence of carbohydrate residues at positions C13 and C19. Typically, on a dry weight basis, the four major steviol glycosides found in the leaves of Stevia are Dulcoside A (0.3%), Reb C (0.6-1.0%), Reb A (3.8%) and Stevioside (9.1%). Other glycosides identified in Stevia extract include Reb B, D, E, and F, Steviolbioside and Rubusoside. Among these, only Stevioside and Reb A are available on a commercial scale. Both Stevioside and Reb A possess undesirable taste attributes such as bitterness, lingering, astringency, and are unable to achieve sweetness equivalency of more than 7-8% of sucrose.
On the other hand, Reb D, Reb E, Reb M, Reb N and Reb O possess better taste attributes and are able to deliver temporal and flavor profile similar to that of sucrose.
Steviol glycosides can be extracted from leaves using either water or organic solvent extraction. Supercritical fluid extraction and steam distillation methods have also been described. Methods for the recovery of diterpene sweet glycosides from Stevia rebaudiana using supercritical CO2, membrane technology, and water or organic solvents, such as methanol and ethanol, may also be used.
Accordingly, there remains a need to develop a method for producing natural reduced or non-caloric sweeteners that provide a temporal and flavor profile similar to that of sucrose.
There remains a further need to develop sweetened consumables, such as beverages and food products, containing natural reduced or non-caloric sweeteners that provide a temporal and flavor profile similar to that of sucrose.